Conservation biologist Thomas Lovejoy, just back from the United Nations climate talks, shared his thoughts with National Geographic on the work under way in Cancun, Mexico, on addressing the role deforestation plays in global warming.

Lovejoy, an innovator who coined the term “biological diversity” and introduced the concept of debt-for-nature swaps, was keynote speaker on one of the panels at Forest Day during the weekend break in the two-week negotiations. It was the fourth Forest Day organized by the nonprofit Center for International Forestry Research.

Delegates at Cancun are not aiming to produce a treaty to replace the Kyoto accord that expires in 2012, but they hope to make progress on several issues—most prominent among them a framework on reducing carbon dioxide emissions from deforestation and degradation.

It is an issue that Lovejoy, a conservation fellow at National Geographic Society, has been talking about for decades. Lovejoy, who also serves as chairman of the advisory council to National Geographic’s Great Energy Challenge, senses a growing agreement in Cancun that something needs to be done on forests.

What is the one thing that you hope the climate negotiators will keep in mind at Cancun?

That the world cannot achieve what it needs on climate without forests playing a major role. At the moment, roughly half of the extra CO2 in the atmosphere is caused by the destruction and degradation of ecosystems, and forests play a large part in that.

It is not only important to stop adding more CO2 from those kinds of activities, it also is wonderful that by doing restoration and reforestation on a serious scale, some of this pesky CO2 can be pulled back into living systems.

I like to talk about using the living planet to make the planet more livable.

What are the greatest misunderstandings about forests in the climate discussion?

One of the important things to recognize is that where there may be, here and there, some role for monocultures of trees, basically it’s going to be important to realize that valuing forests just for their carbon is like valuing a computer chip just for its silicon. Forests are healthier if they are biologically diverse, as they are in nature.

[In the climate discussion], there will sometimes be a lot of focus on what tree grows fastest. I’m not saying there isn’t a place for this. But all of this has to happen in a natural matrix, otherwise it’s not particularly stable.

How much of life on the planet depends on forests?

That’s very hard to say, because we’ve done such a partial job of actually studying life on earth. But in terrestrial ecosystems, easily more than half of all species are in forests, particularly tropical forests.

What gives you hope in your work on forests?

One is the growing recognition of forests in the climate challenge. A second is looking at the positive side of the ledger—seeing the enormous progress, such as in the Brazilian Amazon. (Related: “Amazon Opportunity: Brazil Doesn’t Count on Carbon Market”) A third is anytime you talk to young people—they are bound and determined they are going to fix this.

What have you personally learned on this journey, from research on tropical forests to a focus on their importance in climate change?

I’ve been aware of the latter, both regionally and globally, for easily 30 years. It just takes a while for these things to gain traction. So what I understand today, you might sum up by saying the planet actually works as a biophysical system, not a physical system. It’s biology and physics linked. And basically, we’ve reached the point where we have to proactively manage the planet, so that it starts working in a direction that is better for our future.